JPH08115893A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To provide a method for processing semiconductor devices, wherein variations in traverse rupture strength are reduced, wherein a time required for grinding is shortened, and wherein manufacturing cost is reduced. CONSTITUTION: A semiconductor substrate 28 is ground in such a way that linear streaks 30 parallel with the orientation flat 29 are formed on the underside of the substrate. Semiconductor devices 31 are so positioned that the long side x of each of them will be parallel with the streaks 30 in the semiconductor device 31. This reduces variations in traverse rupture strength from one semiconductor device 31 to another cut from the semiconductor substrate 28. In addition it is possible to obtain a required traverse rupture strength or higher even by grinding with a wheel of lover number. Grinding speed is increased, and a time required for grinding is reduced. One wheel is applicable to a larger number of workpieces, and thus the frequency of wheel change is reduced. This saves labor for grinding, and leads to the reduction of manufacturing cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which a semiconductor substrate is cut and separated to form a plurality of semiconductor devices.

[0002]

2. Description of the Related Art As is well known, before cutting a semiconductor element formed on a semiconductor substrate into individual semiconductor elements, the semiconductor substrate is adjusted in accordance with the size and thickness of an envelope for enclosing the individual semiconductor elements. It is necessary to grind the back surface of the substrate to obtain a predetermined thickness. Two grinding methods called in-feed grinding and creep-feed grinding have been used for grinding the back surface of the substrate.

The prior art will be described below with reference to FIGS. 7 to 10. FIG. 7 is a side view of a main part showing infeed grinding which is a first conventional technique, and FIG. 8 is a back view of a semiconductor substrate ground by the first conventional technique,
FIG. 9 is a side view of an essential part showing creep feed grinding which is a second conventional technique, and FIG. 10 is a back view of a semiconductor substrate ground by the second conventional technique.

In the first conventional in-feed grinding shown in FIGS. 7 and 8, 1 is a rotary support of a grinding machine, and the rotary support 1 is supported by a rotary shaft 2 provided on the lower surface side thereof. Face 3 rotates about a vertical axis. Reference numeral 4 is a disc-shaped grindstone, and the grindstone 4 is provided so that the grinding surface 5 faces the support surface 3 of the rotary support 1 and rotates in a plane parallel to the support surface 3.

The grindstone 4 is rotated by a rotary shaft 6 provided on the upper surface side of the grindstone 4 so as to have a center of rotation that is eccentric to the center of rotation of the support surface 3 of the rotary support 1. Further, the grindstone 4 is fed in a direction perpendicular to the grinding surface 5 as shown by an outline arrow 7 in FIG. 7 during grinding, and the grinding amount is adjusted.

Therefore, when the back surface of the semiconductor substrate 8 is ground, the semiconductor substrate 8 is fixed on the support surface 3 of the rotation support base 1 so that the back surface is the upper side, and the rotation support base 1 is rotated. At the same time, the grindstone 4 is rotated. After that, while the grindstone 4 is rotated, the semiconductor substrate 8 is ground from above by feeding in the direction of the white arrow 7 until the semiconductor substrate 8 reaches a predetermined thickness. On the back surface of the semiconductor substrate 8 after such grinding, as shown in FIG. 8, an arc-shaped striation 9 which turns around the rotation axis 2 is engraved.

Then, the semiconductor substrate 8 whose back surface has been ground is sent to the next step to be cut and separated into a plurality of semiconductor elements 10.

In the second prior art creep feed grinding shown in FIGS. 9 and 10, 11 is a support stand of the grinding machine, the upper surface of which constitutes a support surface 12. Further, 13 is a disk-shaped grindstone, and this grindstone 13 has its lower surface 14
Is provided so as to face the support surface 12 of the support base 11 and to rotate in a plane parallel to the support surface 12 by the rotating shaft 15 provided on the upper surface side.

Further, the grindstone 13 is linearly fed in a direction parallel to the support surface 12 of the support base 11 as shown by an outline arrow 16 in FIG. 9 during grinding. Therefore, the grindstone 13 has the peripheral edge portion 17 and the lower surface 14 as the grinding portion. The amount of grinding performed once is determined by the amount of feed of the grindstone 13 in the axial direction of the rotary shaft 15.

Therefore, when the back surface of the semiconductor substrate 18 is ground, the semiconductor substrate 18 is placed on the support surface 12 of the support base 11.
Is fixed so that its back surface faces upward, and the grindstone 13 is rotated. Subsequently, while the grindstone 13 is rotated, the semiconductor substrate 18 is ground from the side by feeding in the direction of the white arrow 16, and the grindstone 13 is fed out until the entire thickness of the semiconductor substrate 18 reaches a predetermined thickness. Adjust the amount. On the back surface of the semiconductor substrate 18 after such grinding, as shown in FIG. 10, arcuate scratches 19 arranged in one direction are engraved.

Then, the semiconductor substrate 18 whose back surface has been ground
Is sent to the next step and is cut and separated into a plurality of semiconductor elements 20.

The individual semiconductor elements 1 thus formed
On the back surfaces of the semiconductor devices 0 and 20, arcuate scratches 9 and 19 formed on the back surfaces of the semiconductor substrates 8 and 18 by the above-described first and second conventional techniques are divided and carved. 1
The pattern of the scratches 9 and 19 is different for each 0 and 20.

Then, each semiconductor element 1 cut and separated
The semiconductor devices 0 and 20 are encapsulated in a synthetic resin or ceramic envelope through a mounting (die bonding) process, a bonding process, a molding process, and the like.

However, compressive and tensile stresses from the envelope are applied to the semiconductor elements 10 and 20 enclosed in the envelope through the molding process and the like, and this stress causes a part of the semiconductor elements 10 and 20 to be enclosed. Could be destroyed. This is caused by the crushed layer formed on the back surfaces of the semiconductor substrates 8 and 18 by grinding, and when the crushed layer is deep, the bending stress of the semiconductor elements 10 and 20 becomes small and occurs.
The bending stress of the semiconductor elements 10 and 20 varies greatly among the semiconductor chips 10 and 18 cut and separated.

From the above facts, the backside grinding of the semiconductor substrates 8 and 18 is carried out by the grindstones 4 and 13 of high count, and the crushed layer formed is processed to be shallow, and the semiconductor element 10 and
The bending stress of 20 was set to be larger than the stress from the envelope. Grinding with such high-count grindstones 4 and 13 takes time, and the number of pieces that can be processed by one grindstone is small because the grindstone is worn out so frequently that the grindstone has to be replaced frequently and is troublesome. Further, the cost of the grindstone is higher as the number is higher, and the manufacturing cost is high due to the high frequency of replacement.

[0016]

As described above, in the prior art, a semiconductor device obtained by cutting and separating the back surface of a semiconductor substrate and then cutting and separating it does not break when it is enclosed in an envelope made of synthetic resin or the like. Back grinding was performed with a grindstone with fine particles. For this reason, it takes time to grind, labor is required for processing, and the manufacturing cost is high. The present invention has been made in view of such a situation, and an object of the present invention is to reduce the grinding time and the processing time without reducing the variation of the transverse stress, and to reduce the manufacturing cost. It is an object of the present invention to provide a method of manufacturing a semiconductor device.

[0017]

According to a method of manufacturing a semiconductor element of the present invention, a plurality of semiconductor elements are formed by grinding the back surface of a semiconductor substrate to a predetermined thickness and then cutting and separating the semiconductor substrate. In the method of manufacturing a semiconductor element as described above, the back surface of the semiconductor substrate is ground so that substantially linear scratches are formed, and the back surface of the semiconductor substrate has a predetermined thickness. In the method of manufacturing a semiconductor element, which is formed by cutting and separating the semiconductor substrate to form a plurality of rectangular semiconductor elements after grinding, the grinding is performed so that a substantially linear scratch is formed on the back surface of the semiconductor substrate. In addition, the angle between the long side of the semiconductor element and the striation of the semiconductor element is ± 20 degrees or less, and the angle between the striation and the orientation flat is ± 20 degrees. It is characterized by the following.

[0018]

According to the method of manufacturing a semiconductor device having the above-described structure, grinding is performed so that a substantially linear scratch is formed on the back surface of the semiconductor substrate, or a substantially linear scratch is formed on the back surface of the semiconductor substrate. Since the angle formed between the long side of the semiconductor element and the striation of the semiconductor element is set to ± 20 degrees or less while grinding is performed so that the semiconductor element is obtained by cutting and separating the semiconductor substrate. The variation in bending stress can be reduced, and the bending stress can be processed to a predetermined value or more by grinding a low count grindstone. The grinding speed is increased and the grinding time is shortened. The number of grinding with one grindstone increases and the frequency of grindstone replacement is reduced, so that it does not take time and labor and the manufacturing cost can be reduced.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 is a side view of an essential part showing a grinding state, FIG. 2 is a back view of a semiconductor substrate and a semiconductor element after grinding, FIG. 2 (a) is a back view of a semiconductor substrate, and FIG. 2 (b) is a semiconductor. 3 is a back view of the device, FIG. 3 is a back view of the semiconductor device cut and separated from the semiconductor substrate, FIG. 4 is a diagram for explaining a bending stress test method of the semiconductor device, and FIG. 5 is a bending stress. FIG. 6 is a characteristic diagram of FIG. 6, and FIG. 6 is a diagram showing a grindstone cost and a manufacturing cost.

First, prior to the description of the embodiments, the knowledge that has led to the present invention will be described with reference to FIGS.
That is, the semiconductor elements 10 and 20 having various scratches 9 and 19 on the back surface are cut and separated from the semiconductor substrates 8 and 18 ground by the above-mentioned first and second conventional techniques.
Then, the semiconductor elements A, B, C, and D having a rectangular shape were prepared by representing them, and the bending stress of these was measured.

As shown in the back view of FIG. 3, the semiconductor elements A, B, C, and D are semiconductor elements each having a side length of x and y. For example, a (100) plane of a crystal is used for orientation flatness. The angle θ formed by the striations P in the semiconductor element A in FIG. 3A is 10 degrees and the angle formed by the striations P in the semiconductor element B in FIG. θ is 30 degrees, the semiconductor element C in FIG. 3C has an angle θ formed by the scratches P of 45 degrees, and the semiconductor element D in FIG. 3D has an angle θ formed by the scratches P of 90 degrees. Is.

The bending stress of each semiconductor element A, B, C, D was measured by the bending stress test method shown in FIG. A semiconductor element A whose outer dimensions are long side length x = 15 mm, short side length y = 5 mm, and thickness t = 0.45 mm is measured.
B, C, and D are supported by a fulcrum with an interval of 2 l of 10 mm, and the acting force when a force is applied to the center of the fulcrum to break is measured as the transverse stress.

The measurement results are as shown in FIG. 5. The smaller the angle θ formed by the striations P with respect to the side of the length x, the semiconductor element A,
The bending stresses of B, C and D are greatly varied.
Further, as the particles of the grindstone to be ground become finer and the count becomes higher, the bending stress of the semiconductor elements A, B, C, D becomes larger. And the difference in bending stress due to the count of the grindstone, the crush layer formed in the grinding portion when grinding is deep in the low count grindstone, in this case the bending stress is small, in the high count grindstone is shallow, In this case, the bending stress increases.

On the other hand, the compressive and tensile stress applied to the semiconductor element enclosed in the envelope through the molding process is about 15 kg / mm ² , and the bending stress is 15 kg / mm ^2.
If a semiconductor element smaller than kg / mm ² is enclosed, the semiconductor element will be destroyed by the stress applied from the envelope. Therefore, the semiconductor element is required to have a bending stress of about 15 kg / mm ² or more.

Therefore, from FIG. 5, the bending stress is about 15 kg /
Looking at the state of mm ² or more, in the back surface grinding with a grindstone with a count of # 600 or more, the angle θ formed by the striation P with respect to the side of the length x is 20 degrees or less in all semiconductor elements. It should be ground to.

On the other hand, the cost of the grindstone is higher for the higher count ones, as shown by the white circles in FIG. 6, for example. As shown, the manufacturing cost can be reduced sufficiently.

Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 is a side view of an essential part showing a grinding state, FIG. 2 is a back view of a semiconductor substrate and a semiconductor element after grinding, FIG. 2A is a back view of the semiconductor substrate, and FIG.
FIG. 4 is a back view of the semiconductor element.

In FIGS. 1 and 2, reference numeral 21 designates a stationary support stand of the grinding machine in a stationary state, the upper surface of which constitutes a support surface 22. In addition, the cylindrical number 23 is # 12
No. 00 grindstone, the cylindrical surface 24, which is the grinding surface, is used as the support base 2.
The rotary shaft 25 is provided parallel to the first support surface 22 and parallel to the support surface 22 on the upper surface side so as to be rotatable in the arrow 26 direction.

Further, the grindstone 23 is fed linearly in a direction parallel to the support surface 22 of the support base 21 by the movement of the rotary shaft 25 as shown by the white arrow 27 in FIG. 1 during grinding. Has become.

Therefore, when grinding the back surface of the semiconductor substrate 28 using the (100) plane of the crystal, the support 21
The semiconductor substrate 28 is placed on the supporting surface 22 of the above so that the back surface thereof faces upward, and further, the orientation flat 29 is fixed so as to be parallel to the moving direction of the grindstone, and the grindstone 23 is rotated.

Subsequently, while the grindstone 23 is being rotated, the semiconductor substrate 28 is ground in the direction of the arrow 27, and is ground until the entire thickness of the semiconductor substrate 28 reaches a predetermined thickness. As shown in FIG. 2A, a linear scratch 30 parallel to the orientation flat 29 is formed on the back surface of the semiconductor substrate 28 after such grinding.

Then, the semiconductor substrate 28 whose back surface has been ground
Is sent to the next step, and is cut and separated into a plurality of rectangular semiconductor elements 31 whose one side is parallel to the orientation flat 29 and whose long side is x and whose short side is y.

After this, each semiconductor element 31 cut and separated
Is a semiconductor device encapsulated in a synthetic resin or ceramic envelope through a mounting (die bonding) step, a bonding step, a molding step, and the like.

The semiconductor element 31 formed through the above steps has a compressive stress of about 15 kg / mm ² added by the encapsulation in the envelope, and a bending stress about twice the tensile stress. Even if it is enclosed in an envelope and processed into a semiconductor device, it is difficult to destroy. Further, with the grindstone 23 of # 1200 used in this example, it is possible to grind the back surface of the semiconductor substrate 28 having a diameter of 6 inches, for example, from 18,000 to 20000 sheets, while the # With the 2000 grindstone, only about 9000 backside grindings can be performed. Further, semiconductor elements obtained from a semiconductor substrate back-ground with a # 2000 grindstone include those having ridges in a direction perpendicular to the orientation flat and having a bending stress of only the compressive and tensile stresses of the envelope. It was a nuisance.

As described above, according to the present embodiment, the back surface of the semiconductor substrate 28 is ground so as to form the linear scratches 30, and the plurality of semiconductor elements 31 are cut and separated.
It is possible to reduce the variation in the bending stress. Then, the semiconductor element 31 having a high bending stress can be obtained by using the low count grindstone 23, and the grinding time can be shortened, and the number of machining with one grindstone 23 is increased to reduce the frequency of exchanging the grindstone 23. However, it does not take time and effort. Further, since it is possible to use a cheaper grindstone 23, it is possible to reduce the manufacturing cost. In the above-described embodiment, with the grindstone 23 of # 1200, the semiconductor substrate 28 is linearly shaped with the direction parallel to the orientation flat 29 as the grinding direction. Grinding is performed so that the long side x is parallel to the grinding direction.
Although the semiconductor element 31 is cut and separated so as to be parallel to, it may be ground so as to form a substantially linear striation,
Further, by using a grindstone up to # 600 of low count, the semiconductor substrate 28 is ground so that the angle in the grinding direction with respect to the orientation flat 29 is within ± 20 degrees, or the long side x of the semiconductor element 31 and the scratches are formed. Even if the semiconductor device is cut and separated so that the angle is within ± 20 degrees, it does not take time to grind the back surface of the semiconductor substrate 28, and the bending stress of the semiconductor element 31 is larger than the compressive and tensile stresses of the envelope. Even in the state of being processed into, it becomes difficult to break, and the same effect as the embodiment can be obtained.

[0036]

As is apparent from the above description, according to the present invention, the back surface of the semiconductor substrate is ground so that the substantially linear scratches are formed, or the back surface of the semiconductor substrate is substantially linear. The grinding is performed so that a trace is formed, and the angle formed between the long side of the semiconductor element and the striation of the semiconductor element is ± 20 degrees or less. It is possible to obtain the effects that the manufacturing cost can be shortened, the processing cost can be reduced, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side view of an essential part showing a grinding situation in an embodiment of the present invention.

2A and 2B are rear views of a semiconductor substrate and a semiconductor element after grinding in one embodiment of the present invention, FIG. 2A is a rear view of the semiconductor substrate, and FIG. 2B is a rear view of the semiconductor element.

FIG. 3 is a back view of a semiconductor element cut and separated from a semiconductor substrate according to the present invention.

FIG. 4 is a diagram for explaining a bending stress test method for a semiconductor device according to the present invention.

FIG. 5 is a characteristic diagram of bending stress of a semiconductor device according to the present invention.

FIG. 6 is a diagram showing a grindstone cost and a manufacturing cost according to the present invention.

FIG. 7 is a side view of a main part showing in-feed grinding as a first conventional technique.

FIG. 8 is a back view of a semiconductor substrate ground by the first conventional technique.

FIG. 9 is a side view of a main portion showing a second conventional technique, creep feed grinding.

FIG. 10 is a rear view of a semiconductor substrate ground by the second conventional technique.

[Explanation of symbols]

 28 ... Semiconductor substrate 29 ... Orientation flat 30 ... Striations 31 ... Semiconductor element x ... Long side

Claims (3)

[Claims] 1. A method of manufacturing a semiconductor element, comprising: grinding a back surface of a semiconductor substrate to a predetermined thickness; then cutting and separating the semiconductor substrate to form a plurality of semiconductor elements. A method of manufacturing a semiconductor element, which comprises grinding so that a substantially linear scratch is formed on the back surface. 2. A method of manufacturing a semiconductor element, comprising: grinding a back surface of a semiconductor substrate to have a predetermined thickness, and then cutting and separating the semiconductor substrate to form a plurality of rectangular semiconductor elements. The back surface of the semiconductor substrate is ground so as to form substantially linear scratches, and the angle between the long side of the semiconductor element and the scratches of the semiconductor element is ± 20 degrees or less. Manufacturing method of semiconductor device. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the angle formed between the streak and the orientation flat is ± 20 degrees or less.